Here are two short articles with interesting contrast. BTW, in the current issue of the IEEE Communications Magazine is a series of articles on MIMO wireless systems (multiple in, multiple out, otherwise known as space time codes). IEEE 802.16a (WiMAX) includes MIMO and COFDM in its wireless interface, which stretches its spectral efficiency right up close to the Shannon limit. WiMAX uses multiple channel bandwidths, from 1.5 MHz to 20 MHz, but possibly more depending what the frequency band allows. The receiver sensitivity spec is interestingly not very remarkable. For a familiar combination, 64-QAM, 3/4 FEC, 6 MHz channel, the required sensitivity is -70 dBm. Nothing spectacular. ATSC I think uses -85 dBm as a planning factor, at the same spectral efficiency. WiMAX uses the basic convolutional and Reed-Solomon concatenated FEC, same as DTT systems, but optionally allows turbo block codes vs. RS. In one example cited in one of the IEEE magazine articles, it seems to exceed the Shannon limit, but this must be only because they are accepting a significant error rate in that example. Also BTW, MIMO can consist of multiple transmitting antennas and multiple receive antennas, all sending and receiving the same information bit stream (perhaps arranged in different order from each antenna). However, its full potential is achieved when the multiple transmit antennas send different parallel bit streams, over the same RF channel, and the receiver with equal number of receive antennas recombines these into one high speed bit stream. Fancy stuff. Bert ----------------------------------- WiMAX to be 'clear winner' in broadband wireless John Walko Dec 07, 2004 (7:19 AM) URL: http://www.commsdesign.com/showArticle.jhtml?articleID=3D55300022 LONDON - WiMAX and other emerging high-speed wireless technologies will capture more than 40 percent of the wireless broadband business over the next few years, leaving 3G with less than 60 percent of the market in 2009, according to a just published report from TelecomView. The report suggests the new technologies provide significant opportunities for both incumbent and competitive carriers. "Our forecasts show that WiMAX will be the clear winner amongst the new high-speed wireless technologies," said Ian Cox, principal analyst at TelecomView and co-author of the report. "WiMAX will pick up 70 percent of this new market segment by 2009 due to its higher performance and flexibility compared to the alternatives. 3G will be important for its mobility, but WiMAX will directly compete with DSL." The report, which covers deployments, regulatory issues and analyses of the business case for both urban and rural areas, suggests that the return on investment (ROI) for these new wireless broadband technologies is significantly better than for 3G. According to Bob Larribeau, the other author of the study and also a principal analyst at TelecomView, said: "In fact, the business case for WiMAX, in particular, is close to that for wireline DSL, which makes it an excellent broadband technology alternative." Copyright 2003 CMP Media --------------------------------------- Sprint spends $3 billion to upgrade mobile network John Walko Dec 07, 2004 (11:13 AM) URL: http://www.commsdesign.com/showArticle.jhtml?articleID=3D55300094 LONDON - Sprint Corp. is extending its supply agreements with Lucent Technologies, Nortel and Motorola in an upgrade of its cellular network valued at $3 billion over the next three years, the operator said Tuesday (December 7th). Lucent said its deals for base station gear for third generation network based on CDMA2000 1xEV-DO technology and IP Multimedia Subsystems should be worth over $1.5 billion over the three years. Nortel puts the value of its contracts for CDMA 1X basestations, controllers and switching platforms at $1 billion, while Motorola suggests its share of the extension to the PCS network extension is worth $450 million. Sprint said in June it would add EV-DO capabilities to its network in major metropolitan areas in 2005. The company said this portion of the upgrade would cost $1 billion, with the majority being spent in 2005. The $3 billion also includes options for 1xEV-DV Release D broadband speed upgrades, with all three manufacturers saying they are in the running to supply gear for this extension. Copyright 2003 CMP Media ---------------------------------------------------------------------- You can UNSUBSCRIBE from the OpenDTV list in two ways: - Using the UNSUBSCRIBE command in your user configuration settings at FreeLists.org - By sending a message to: opendtv-request@xxxxxxxxxxxxx with the word unsubscribe in the subject line.